Family and friends of 16-year-old Queensland high school student Larissa Beilby hold grave concerns for the teenager, who last made contact with her family and friends on June 18.

Queensland Police are seeking 34-year-old Queensland man Zlatko Sikorsky as a person of interest in the case.

Police believe Sikorsky may be able to assist them after a woman's body was found stuffed into a barrel in the back of an abandoned ute in a gated mobile home park Stapylton, south of Brisbane on Wednesday.

A witness who helped the ute enter the gated complex recalled seeing a human arm sticking out of the barrel in the back of the vehicle.

While the victim is yet to be formally identified, there are fears it could be Beilby, who police say was "associated" with Sikorsky.

Zlatko Sikorsky (pictured) is believed to be travelling in a silver 2014 Holden Commodore with a sunroof.

Beilby was reported missing from her home in the Brisbane suburb of Sandgate on June 15 and last made contact with family and friends on June 18.

Here's what we know so far about the troubling case.

Beilby was living in a halfway house

The teenager, originally from Adelaide, reportedly left the home she shared with her father, sister and brother over a disagreement and had been living in youth accommodation.

She had recently fled a violent relationship

According to The Courier-Mail, Beilby had been seeing another man before linking up with Sikorsky but left him after telling friends she was "fearful" of him. She also reportedly told friends she was concerned Sikorsky would discover her age and that he had a gun.

Sikorsky has a criminal history

Court documents show Sikorsky, who runs a cleaning business, has a long list of offences dating back to 2010.

Most recently, he was sentenced to five years prison in 2016 for charges including extortion, deprivation of liberty and armed robbery. He was released on parole.

The Age reports that in 2013 he was sentenced to less than a year in prison for over 60 offences, including possessing dangerous drugs, disqualified driving and stealing.

Members of the public have been urged not to approach him but rather to immediately contact police by calling 000. It is believed he might be armed.

Deilby was skipping school, according to friends

She was in year 12 at Craigslea State School in Brisbane's north but hadn't been attending classes, Seven News reports.

Her family have asked for an end to 'speculation'

Deilby's older sister Deanna took to Facebook to warn family and friends of "false information" being circulated.

"As a family we would like to notify everyone that the information circuling [sic] the media has not come from us, at this point in time it is all speculation," she said.

"We have not supplied the media with ANY information and nor shall we until we are provided with all the facts from the police. To hear such horrible lies and twisted rumours is breaking our hearts even more," she added.

Deilby is an active social media user

Beilby, known as 'Riss' to her friends, was a regular poster on Instagram on Facebook, sharing selfies and photos of her new haircut or makeup looks to her 1400 followers. Her most recent Instagram post was on June 8. When she stopped posting on social media, friends grew concerned for her wellbeing.

"She [Beilby] hasn't been on social media for a week which is very weird for her, no-one has seen her since 15th of June," Beibly's sister Deanne wrote in a social media post.

She lost her mother in 2006

Deilby was only four years old when her mother Karen passed away at the age of 32, Nine News reports. The family was living in South Australia at the time, but moved to Queensland soon after.

A post mortem examination on the body found in the back of the ute is expected today to identify the victim. A manhunt for Sikorsky is ongoing.

Anyone with information is encouraged to contact Policelink on 131 444 or Crime Stoppers on 1800 333 000 or via crimestoppersqld.com.au 24hrs per day.